Messages are usually text based displays designed to update the computer user on system status or to issue warnings regarding specific operations.

Messages that contain numerical data usually have the numerical data converted to string format prior to display. Most messages are programmed responses to certain default conditions or sets of programming flags. Other messages provide standard warnings against the deletion of files or the opening of insecure documents. Internet messages often update the user on the status of a page search (e.g., "Page not found messages") or warn against the sending of information over an insecure link.

Although often similar in appearance, messages differ from dialog boxes in that messages do not require a user response. Modified message formats may ask the user to acknowledge the message by pressing a prompt key before the message is removed from the screen and operations or programs proceed.

Programming or software objects also communicate via messages, and these messages become a vital part of program operation. Because of this, programming objects do not need to be in the same program, process or physical machine--as long as there is an establishable communication link between the objects. A program may set a certain number of flags (indirect message) or send a direct message to a subroutine to execute a certain portion of a program. The sending object is, in a programming sense, sending a message to the second object so that the second object performs a specific operation.

Although messages may have multiple components or parameters, almost all messages contain at least three vital components. First, the message must contain the address of the object to which it is directed. Second, the message must contain sufficient information to direct the receiving object what to do when the message is received. Finally, the message must contain any information required to perform the desired operation(s).